Prediction Model with Validation for Polioseronegativity in Malnourished Children from Poliomyelitis Transmission High-Risk Area of the Democratic Republic of the Congo (DRC).

Background: Malnutrition is identified as a risk factor for insufficient polio seroconversion in the context of a vaccine-derived poliovirus (VDPV) outbreak-prone region. In the Democratic Republic of Congo (DRC), underweight decreased from 31% (in 2001) to 26% (in 2018). Since 2004, VDPV serotype 2 outbreaks (cVDPV2) have been documented and were geographically limited around the Haut-Lomami and Tanganyika Provinces. Methods: To develop and validate a predictive model for poliomyelitis vaccine response in malnourished infants, a cross-sectional household study was carried out in the Haut-Lomami and Tanganyika provinces. Healthy children aged 6 to 59 months (n=968) were enrolled from eight health zones (HZ) out of 27, in March 2018. We performed a bivariate and multivariate logistics analysis. Final models were selected using a stepwise Wald method, and variables were selected based on the criterion p < 0.05. The association between nutritional variables, explaining polio seronegativity for the three serotypes, was assessed using the receiver operating characteristic curve (ROC curve). Results: Factors significantly associated with seronegativity to the three polio serotypes were underweight, non-administration of vitamin A, and the age group of 12 to 59 months. The sensitivity was 10.5%, and its specificity was 96.4% while the positive predictive values (PPV) and negative (PNV) were 62.7% and 65.3%, respectively. We found a convergence of the curves of the initial sample and two split samples. Based on the comparison of the overlapping confidence intervals of the ROC curve, we concluded that our prediction model is valid. Conclusion: This study proposed the first tool which variables are easy to collect by any health worker in charge of vaccination or in charge of nutrition. It will bring on top, the collaboration between the Immunization and the Nutritional programs in DRC integration policy, and its replicability in other low- and middle-income countries with endemic poliovirus.

Corrigendum to "Examination of scenarios introducing rubella vaccine in the Democratic Republic of the Congo" [Vaccine: X 9 (2021) 100127].

[This corrects the article DOI: 10.1016/j.jvacx.2021.100127.].

Examination of scenarios introducing rubella vaccine in the Democratic Republic of the Congo.

BACKGROUND: Rubella vaccine has yet to be introduced into the national immunization schedule of the Democratic Republic of the Congo (DRC); the current burden of congenital rubella syndrome (CRS) is unknown and likely to be high. An important consideration prior to introducing rubella containing vaccine (RCV) is the potential inverse relationship between RCV coverage and CRS incidence. Increasing RCV coverage will also increase in the average age of infection. Cumulative infections across all age groups will decrease, but the number of infections in age groups vulnerable to CRS may increase. METHODS: Rubella transmission dynamics in the DRC were simulated using a stochastic agent-based model of transmission. Input parameter values for known properties, demographic variables, and interventions were fixed; infectivity was inferred from seropositivity profiles in survey data. RESULTS: Our simulations of RCV introduction for the DRC demonstrate that an increase in CRS burden is unlikely. Continued endemic transmission is only plausible when routine immunization coverage is less than 40% and follow-up supplemental immunization activities have poor coverage for decades. CONCLUSION: Increased vaccination coverage tends to increase the annual variability of CRS burden. Simulations examining low vaccination coverage and high mean CRS burden are outbreak prone, with multiple years of reduced burden followed by acute outbreaks. These outcomes contrast simulations with no vaccination coverage and high mean CRS burden, which have more consistent burden from year to year.

Increasing Ebola transmission behaviors 6 months post-vaccination: Comparing vaccinated and unvaccinated populations near 2018 Mbandaka Ebola outbreak in the Democratic Republic of Congo.

BACKGROUND: In 2018, the Democratic Republic of the Congo (DRC) declared its 9th and 10th Zaire ebolavirus (EBOV) outbreaks, in the Equateur province (end: July 2018), and in the eastern provinces including North Kivu (end: June 2020). The DRC Ministry of Health deployed the rVSV-vectored glycoprotein (VSV-EBOV) vaccine in response during both outbreaks. METHODS: A cohort of vaccinated and unvaccinated individuals from the Equateur province were enrolled and followed prospectively for 6 months. Among participants included in this analysis, 505 were vaccinated and 1,418 were unvaccinated. Differences in transmission behaviors pre- and post- outbreak were identified, along with associations between behaviors and vaccination. RESULTS: There was an overall increase in the proportion of both unvaccinated and vaccinated individuals in Mbandaka who participated in risky activities post-outbreak. Travel outside of the province pre-outbreak was associated with vaccination. Post-outbreak, vaccinated individuals were less likely to participate in funeral traditions than unvaccinated individuals. CONCLUSION: A net increase in activities considered high risk was observed in both groups despite significant efforts to inform the population of risky behaviors. The absence of a reduction in transmission behavior post-outbreak should be considered for improving future behavior change campaigns in order to prevent recurrent outbreaks.

Measles antibody levels among vaccinated and unvaccinated children 6-59 months of age in the Democratic Republic of the Congo, 2013-2014.

BACKGROUND: Measles is endemic in the Democratic Republic of the Congo (DRC), and 89-94% herd immunity is required to halt its transmission. Much of the World Health Organization African Region, including the DRC, has vaccination coverage below the 95% level required to eliminate measles, heightening concern of inadequate measles immunity. METHODS: We assessed 6706 children aged 6-59 months whose mothers were selected for interview in the 2013-2014 DRC Demographic and Health Survey. History of measles was obtained by maternal report, and classification of children who had measles was completed using maternal recall and measles immunoglobulin G serostatus obtained from a multiplex chemiluminescent automated immunoassay dried blood spot analysis. A logistic regression model was used to identify associations of covariates with measles and seroprotection, and vaccine effectiveness (VE) was calculated. RESULTS: Out of our sample, 64% of children were seroprotected. Measles vaccination was associated with protection against measles (OR: 0.15, 95% CI: 0.03, 0.81) when administered to children 12 months of age or older. Vaccination was predictive of seroprotection at all ages. VE was highest (88%) among children 12-24 months of age. CONCLUSION: Our results demonstrated lower than expected seroprotection against measles among vaccinated children. Understanding the factors that affect host immunity to measles will aid in developing more efficient and effective immunization programs in DRC.

Changes in childhood vaccination coverage over time in the Democratic Republic of the Congo.

Despite increased vaccination rates, the burden, morbidity and mortality associated with vaccine preventable diseases remains high. In the Democratic Republic of the Congo (DRC), potentially unreliable data and geographically varied program provision call for a better understanding of vaccination coverage and its changes over time at the country and province level. To assess changes in the proportion of children who were fully vaccinated over time in the DRC, vaccination histories for children 12-59 months of age were obtained from both the 2007 and 2013-2014 Demographic and Health Surveys (DHS). Changes were assessed, both at the country- and province-levels, to identify potential geographic variations. Vaccination coverage improved 70% between the DHS waves: 26% compared to 44% of 12-59 month-old children met full vaccination criteria in 2007 and 2013-2014, respectively (n2007 = 3032 and n2013-14 = 6619). Similarly, there was an overall trend across both DHS waves where as year of birth increased, so did vaccination coverage. There was geographic variation in immunization changes with most central and eastern provinces increasing in coverage and most northern, western and southern provinces having decreased vaccination coverage at the second time point. Using nationally representative data, we identified significant changes over time in vaccination coverage which may help to inform future policy, interventions and research to improve vaccination rates among children in the DRC. This study is the first of its kind for the population of DRC and provides an important initial step towards better understanding trends in vaccination coverage over time.

Prevalence of Rubella Antibodies Among Children in the Democratic Republic of the Congo.

BACKGROUND: While generally mild in children, rubella infection in early pregnancy can lead to miscarriage, fetal death or congenital rubella syndrome. Rubella vaccination is not yet available as a part of routine immunization in the Democratic Republic of the Congo (DRC), and the burden of infection is unknown. METHODS: In collaboration with the 2013-2014 DRC Demographic and Health Survey, a serosurvey was carried out to assess population immunity to vaccine-preventable diseases. Dry blood spot samples collected from children 6-59 months of age were processed using the Dynex Technologies Multiplier FLEX chemiluminescent immunoassay platform (Dynex Technologies, Chantilly, VA). RESULTS: Among the 7195 6- to 59-month-old children, 33% were positive and <1% indeterminate for rubella antibodies in weighted analyses. Seroprevalence was positively associated with age of the child and province, with seropositivity highest in Bandundu (53%) and lowest in Kasai-Oriental (20%). In multivariate analyses, serologic evidence of infection was associated with age of the mother and child, socioeconomic status and geographic location. CONCLUSIONS: Rubella infection is prevalent among children in the DRC, and while most seroconversion occurs in young children, a significant proportion of children remain at risk and may enter reproductive age susceptible to rubella infection. While not currently in place, implementation of a surveillance program will provide improved estimates of both rubella virus circulation and the burden of congenital rubella syndrome. Such information will play an important role in future policy decisions, vaccine delivery strategies and may provide a basis upon which the effectiveness of rubella antigen introduction may be assessed.

Vaccination coverage and factors influencing routine vaccination status in 12 high risk health zones in the Province of Kinshasa City, Democratic Republic of Congo (DRC), 2015.

INTRODUCTION: Vaccination coverage of the first dose of diphtheria-tetanus-pertussis-hepatitis B-Haemophilus influenza type b (pentavalent) vaccine for the City-Province of Kinshasain the years 2012 - 2014 wasbelow the national objective of 92%, with coverage less than 80% reported in 12 of the 35 health zones (HZ). The purpose of this study was to discern potential contributing factors to low vaccination coverage in Kinshasa. METHODS: We conducted a multi-stage cluster household study of children 6 - 11 months in households residing in their current neighborhood for at least 3 months in the 12 high risk HZ in Kinshasa. Additional information on vaccination status of the children was collected at the health facility. RESULTS: Of the 1,513 households with a child 6-11 months old, 81% were eligible and participated. Among the 1224 children surveyed, 96% had received the first dose of pentavalent vaccine; 84% had received the third dose; and 71% had received all recommended vaccines for their age. Longer travel time to get to health facility (p=0.04) and shorter length of residence in the neighborhood (p=0.04) showed significant differences in relation to incomplete vaccination. Forty percent of children received their most recent vaccination in a facility outside of their HZ of residence. CONCLUSION: This survey found vaccination coverage in 12 HZs in Kinshasa was higher than estimates derived from administrative reports. The large percentage of children vaccinated outside of their HZ of residence demonstrates the challenge to use of the Reaching Every District strategy in urban areas.

Evidence of Mumps Infection Among Children in the Democratic Republic of Congo.

BACKGROUND: Mumps is an acute viral infection and while the infection is usually mild, complications can lead to permanent sequelae including brain damage and deafness. The burden of mumps is currently unknown the Democratic Republic of Congo (DRC), we therefore assessed susceptibility to mumps infection among children 6-59 months of age. METHODS: In collaboration with the 2013-2014 DRC Demographic and Health Survey, we conducted a serosurvey to assess population immunity to vaccine preventable diseases. Dried blood spot samples were collected from children 6 to 59 months of age and processed at the UCLA-DRC laboratory in Kinshasa, DRC using the Dynex Technologies Multiplier FLEX chemiluminescent immunoassay platform (Dynex multiplex assay, Chantilly, VA). Logistic multivariate analyses were used to determine risk factors for mumps seropositivity. RESULTS: Serologic and survey data were matched for 7195, 6-59 month-old children, among whom 22% were positive and 3% indeterminate for mumps antibodies in weighted analyses. In multivariate analyses, the odds of seropositivity increased with increasing age, female gender, number of children in household, increasing socioeconomic status and province (Kinshasa with the highest odds of positive test result compared with all other provinces). CONCLUSION: These data suggest that mumps virus is circulating in DRC and risk of exposure increases with age. At present, the introduction of a combined measles-mumps-rubella vaccine remains unlikely, as the capacity to maintain adequate vaccine coverage levels for routine immunization must be improved before additional antigens can be considered for the routine immunization schedule.